1. Field
The disclosed concept relates generally to monitoring circuits, and in particular, to monitoring circuits for use in split phase electrical distribution configurations.
2. Background Information
Split phase electrical distribution configurations are well known in the art. One known split phase electrical distribution configuration is the 120/240 single phase electrical distribution configuration shown in FIG. 1. The 120/240 single phase electrical distribution configuration is used in many residential and commercial applications in North America.
Referring to FIG. 1, the 120/240 single phase electrical distribution configuration has first and second lines L1,L2 and a neutral N. In the 120/240 single phase electrical distribution configuration, the line-neutral voltages V1,V2 are 120V and the line-line voltage V3 is 240V under normal operating conditions. A first facility load R1LOAD is electrically connected between the first line L1 and the neutral N and a second facility load R2LOAD is electrically connected between the second line L2 and the neutral N. The purpose of the neutral N is to maintain the equal voltages across the first and second facility loads R1LOAD,R2LOAD, regardless of whether the facility loads R1LOAD,R2LOAD are unbalanced.                However, if the neutral N is broken or missing, and the facility loads R1LOAD,R2LOAD are unbalanced, then the voltages across the facility loads R1LOAD,R2LOAD become unequal. The unequal voltages can create an overvoltage condition (e.g., without limitation, applying an excessive voltage to an appliance) which can damage equipment as well as create a dangerous situation. It would therefore be desirable to monitor the status of the neutral wire.        
There is room for improvement in monitoring circuits.